As part of its unprovoked invasion, Russia has been firing massed waves of drones and missiles into Ukraine for years, though the tempo has been raised dramatically in recent months. Barrages of 700-plus drones now regularly attack Ukraine during overnight raids. Russia also appears to have upped the ante dramatically by sending at least 19 drones into Poland last night, some of which were shot down by NATO forces.
Many of these drones are Shahed/Geran types built with technology imported from Iran, and they have recently gained the ability to fly higher, making shootdowns more difficult. Given the low cost of the drones (estimates suggest they cost a few tens of thousands of dollars apiece, and many are simply decoys without warheads), hitting them with multimillion-dollar missiles from traditional air defense batteries makes little sense and would quickly exhaust missile stocks.
So Ukraine has adopted widespread electronic warfare to disrupt control systems and navigation. Drones not forced off their path are fought with mobile anti-aircraft guns, aircraft, and interceptor drones, many launched from mobile fire teams patrolling Ukraine during the night.